Image forming device and image forming method

ABSTRACT

An image forming device for adequately forming an image in which images overlap one another. The priority order (display order) of the images overlapping with one another is judged for the area where images of different attributes overlap with one another. When the priority rank of a three-dimensional image is high, a planar image in the overlapping area is deleted, or a three-dimensional image is formed on a planar image. When the rank of a planar image is high, only the color image of a three-dimensional image in the overlapping area is deleted, and a planar image is formed using foaming toner.

TECHNOLOGICAL FIELD

The present invention relates to an image forming device and an imageforming method, and more particularly, to an image forming device forprinting a composite image with which a plurality of images areoverlapped one over another and an image forming method for the same.

BACKGROUND TECHNOLOGY

With the advance of the application software for image drawing, imageshaving a variety of colors and patterns are processed and edited onpersonal computers (PC) and work stations (WS).

Further, with the advance of the image forming devices using theelectrophotography method, the ink jet method, and the like, it has beenmade possible to print the images created by such application softwareon paper or the like with high precision.

Conventionally, when a composite image having an overlapping area whereparts of different images (figures), characters, and the like areoverlapped one over another is to be represented by using applicationsoftware, an image having a higher priority rank has been preferentiallyrepresented on the basis of priority ranks (display order) which arenormally established for the images.

On the application software, such a composite image is handled as if, inthe overlapping area, both images were given. Conventionally, when animage is to be formed with an image forming device, only the image whichpriority rank is higher has been formed into an image if it is opaque.On the other hand, if the image having a higher priority rank istransparent, the image processing has been separately applied to theoverlapping area so as to form an image in which both the images areblended into one.

This is because, for example, when the image which priority rank ishigher is opaque, the image which priority rank is lower will not showup to the surface, thus there is no need for forming the image having alower priority rank into an image. If the image which priority rank ishigher is formed into an image on the image formed from the image havinga lower priority rank, the geometry and color of the image with a lowerpriority rank can have an influence on the image having a higherpriority rank.

As an example of such a technology, JP H09-104987 A discloses thetechnology which, by writing a divided job sequence into a map memory,and developing the pixel information in accordance with the result ofthe overlapping judgment, efficiently carries out detection of thedrawing elements which are overlapped one over another, thus preventingthe effect of the parallel processing of drawn images from beingcancelled.

In recent years, with the advance of the image processing apparatus,there have arisen various demands for the processing up to the stage ofimage formation.

For example, in order to introduce the electrophotography type imageforming device, which eliminates the need for photochemical process,into the light printing market, an electrophotography type image formingdevice which can provide a still higher quality of image has beenrequired.

In some applications of the electrophotography, there arises a case inwhich images are formed having a different attribute, such as anembossed image, which has an attribute of height in addition to that ofplanarity using only color toners, such as embossed printing with whichan embossed image is formed by using foaming toners in addition to theconventional color toners.

With these technologies, how the image formation is carried out in thearea where the toners are overlaid one over another (in the overlappingarea where images are overlapped one over another) is an extremelyimportant problem.

With conventional image forming devices, however, an area where imagesare overlapped one over another, and an area where images are notoverlapped have been differently processed for image formation. Thus,such a problem arose that an error is caused between the respectiveareas, resulting in a gap being produced at the boundary between theimages formed. Also, when the image having a higher priority rank is tobe overlapped on the image with a lower one so as to generate a delicateexpression for the image formed, it was very difficult to cope with thesituation.

In addition, in such a case as that when images having differentattributes, i.e., a planar image, which is represented on a planarsurface only with color toners, and an embossed image, which representsa height by using foaming toners, are to be represented, it is desirableto carry out image formation also for the image with a lower priorityrank.

In view of the above problems, the purpose of the present invention isto provide an image forming device which is capable of adequatelyforming an image for the areas where images are overlapped one overanother.

DISCLOSURE OF THE INVENTION

According to an image forming device of the present invention, the imageforming device which forms an image into an image on a recording paper,comprises means for determining that there is an area where two imagesare overlapped one over another at least partially; and means fordetermining attributes of these two images, wherein for an image havinga specific attribute of these two images, no image is deleted even inthe overlapping area.

Also, an image forming device which forms an image into an image on arecording paper, comprises means for determining that there is an areawhere two images are overlapped one over another at least partially;means for determining priority ranks which represent a top or bottom inoverlapped status of these two images in the overlapping area; and meansfor forming an image which priority rank is lower, and thereupon,forming an image which priority rank is higher, in the overlapping area.

Also, there is further provided means for determining attributes ofthese two images in the overlapping area, wherein these two images arean image having a specific attribute, and an image having anotherattribute, when the image having the specific attribute has a priorityrank lower than that for the image having the another attribute, theimage having the specific attribute is formed into an image, andthereupon, the image having the another attribute is formed into animage in the overlapping area, and when the image having the specificattribute has a priority rank higher than that for the image having theanother attribute, the image having the specific attribute is formedinto an image, and the image having another attribute being not formedinto an image in the overlapping area.

Also, there is further provided means for selecting either forming theimage having the specific attribute in the overlapping area into animage, and thereupon, forming the image having the another attributeinto an image, or forming the image having the specific attribute in theoverlapping area into an image, and not forming the image having theanother attribute into an image, when the image having the specificattribute has a priority rank lower than that for the image having theanother attribute.

Also, when both of these two images are the image having the specificattribute or the image having the another attribute, the image which hasa higher priority rank is formed into an image, and the image which hasa lower priority rank is not formed into an image in the overlappingarea.

Also, an attribute of the image having the specific attribute is anembossed image.

Next, an image forming method according to the present invention, theimage forming method for forming an image into an image on a recordingpaper, comprises the steps of determining an overlapping area where twoimages are overlapped at least partially, determining priority rankswhich represent a top or bottom in an overlapped status of these twoimages in the overlapping area, and forming an image which has a lowerpriority rank into an image, and thereupon, forming the image which hasa higher priority rank into an image.

Also, there is further provided the step of determining attributes ofthese two images in the overlapping area, wherein, when it is determinedthat both of these two images are an image having a specific attributeand an image having another attribute, the image having the specificattribute is formed into an image, and thereupon, the image having theanother attribute is formed into an image in the overlapping area whenthe image having the specific attribute has a priority rank lower thanthat for the image having the another attribute, and the image havingthe specific attribute is formed into an image, and the image having theanother attribute is not formed into an image in the overlapping areawhen the image having the specific attribute has a priority rank higherthan that for the image having the another attribute.

Also, an attribute of the image having the specific attribute is anembossed image.

Thus, with the present invention, even when a plurality of images areoverlapped one upon anther, the respective images can be represented,regardless of whether or not the images have different attributes, onebeing a planar image and the other being a stereo one.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic configuration drawing illustrating an exampleof system comprising an image forming device according to the presentinvention;

FIG. 2 is a diagrammatic configuration drawing illustrating an exampleof image forming device according to the present invention;

FIG. 3 is a diagrammatic block diagram illustrating a system comprisingan image forming device in the present embodiment;

FIG. 4 is a flow chart illustrating the flow of image data processing bythe image forming device in the present embodiment;

FIG. 5 is a flow chart illustrating the flow of image processing of Case1 in the present embodiment;

FIGS. 6( a) through 6(c) are conceptual drawings illustrating an exampleof image processing of Case 1 in the present embodiment;

FIG. 7 is a flow chart illustrating the flow of image processing of Case2 in the present embodiment;

FIGS. 8( a) through 8(c) are conceptual drawings illustrating an exampleof image processing of Case 2 in the present embodiment;

FIGS. 9( a) and 9(b) are conceptual drawings illustrating an example ofimage processing of Case 2 in the present embodiment;

FIG. 10 is a conceptual drawing illustrating an example of imageprocessing of Case 3 in the present embodiment;

FIGS. 11( a) through 11(c) are conceptual drawings illustrating anexample of image processing of Case 3 in the present embodiment; and

FIGS. 12( a) and 12(b) are conceptual drawings illustrating an exampleof image processing of Case 3 in the present embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinbelow, an embodiment of the image forming device and the imageformation method according to the present invention will be described indetail with reference to the accompanying drawings.

FIG. 1 is a diagrammatic configuration drawing illustrating a systemincluding an image forming device according to the present invention.

This image forming device 10 is configured such that it carries outimage formation on the basis of the image data transmitted from an imageediting device 20, such as a personal computer (PC) or a work station(WS).

In the image editing device 20, application software for carrying outimage edition is installed, which allows editing/processing of an imageby operating an operation section 22, such as a keyboard or a mouse,while confirming the image which is displayed on a display 21.

The image forming device 10 comprises an image forming section 11 forcarrying out image formation, paper trays 12 for accommodating papers torecord images on them, and a recording paper discharge section 13 fordischarging a recording paper on which an image is recorded.

The image forming device 10 and the image editing device 20 areconnected to each other through a communication cable 30, such as aserial cable or a network cable, or communication means (not shown),such as a radio communication apparatus.

FIG. 2 is a diagrammatic configuration drawing illustrating an exampleof image forming device according to the present invention. In the imageforming section 11, an image writing device 14, photosensitive media 15,toner bottles 16, developing equipment 17, and an intermediate transferbelt 18 are provided.

Image information transmitted from the image editing device is convertedinto an image formation data to be transmitted to the image writingdevice 14, which irradiates laser beam or the like onto thephotosensitive medium 15 to create a latent image thereon.

In order to write the image with Y (yellow), M (magenta), C (cyan), K(black) and foaming toners, five toner bottles 16 which respectivelycontain Y, M, C, K and foaming toners are disposed in the image formingsection 11. From the toner bottles 16, the toners are carried to thedeveloping equipment 17, the toners being developed on thephotosensitive medium 15 which has been provided with a latent image.

The toner which has been developed on the photosensitive medium 15 istransferred to the intermediate transfer belt 18, and while a recordingpaper taken out from the paper tray 12 is passed through a secondarytransfer section 19, after being passed through the paper transport path(not shown), the image transferred to the intermediate transfer belt 18is transferred to the recording paper, which, after being heated by theimage fixing section (not shown) for fixing the image, is dischargedfrom the recording paper discharge section 13 to the outside of theimage forming device 10.

In the present embodiment, in addition to the YMCK, a photosensitivemedium is provided to develop the foaming toner in order to form anembossed image together with a color image which is formed by placingcolor toners on the surface. However, the configuration may be such thatan embossed image is formed by replacing any one of the bottles (K tonerbottle, for example) with a toner bottle containing the foaming toner orby using some other method.

Next, referring to FIG. 3, the flow of processing until the image datais formed into an image will be described.

First, by using application software 40 installed in the image editingdevice 20, such as a PC or a work station, an image, such as a characteror a figure, is processed/edited to carry out the image drawing (at step100).

Then, by using a printer driver 41 installed in the image editing device20, the image data for the image which has been drawn is converted into“page description language” with which enlargement, turning,deformation, and the like of the image can be freely performed, such asPostScript (trademark of Adobe Systems, Inc.) (at step 110).

The image data which has been converted into that in the Postscript istransmitted to the controller in the image forming device 10 through thecommunication cable 30, such as a serial cable or a network cable, whichis connected to the image editing device 20. In the controller, theimage processing is performed on the area where figures such as circleand square, and image portions such as the text area, are overlapped oneover another (at step 120).

Then, on the basis of the image data of the overlapping area on whichthe image processing has been performed, the image writing device 14irradiates laser beam or the like onto the photosensitive medium 15 tocreate image formation data to be used in writing the image (at step130).

The image formation data thus created is transmitted to the imagewriting device, and on the basis of this image formation data, laserbeam or the like is irradiated onto the photosensitive medium 15. Then,with the image formation process as described with reference to FIG. 2,the image is transferred to the recording paper to form an image thereon(at step 140).

Referring to FIG. 4, the flow of image processing applied to the imagein the overlapping area will be described in detail.

First, it is determined whether the image for the image data transmittedfrom the image editing device 20 has an overlap between images, such asfigures and characters (at step 200), and when it is determined thatimages are not overlapped (NO at step 200), image formation data iscreated from the image data (step 290).

When it is determined that images are overlapped (YES at step 200), theoverlapped images are identified (at step 210).

Here, in the present embodiment, it is assumed that two images, i.e.,image A and image B are overlapped one over another.

Then, it is determined whether the image A is a planar image in whichthe image is planarly expressed (at step 220), and when it is determinedthat the image A is a planar image (YES at step 220), it is determinedwhether the image B is a planar image (at step 230).

When it is determined that the image B is a planar image (YES at step230), the image processing in the overlapping area is performed as Case1(at step 250), and when it is determined that the image B is not aplanar image (NO at step 230), the image processing in the overlappingarea is performed as Case 2(at step 260).

At the step 220, when it is determined that the image A is not a planarimage (NO at step 220), it is determined whether the image B is a planarimage (at step 240).

When it is determined that the image A is a planar image (YES at step240), the image processing is applied to the overlapping area as Case2(at step 260), and when it is determined that the image B is not aplanar image (NO at step 240), the image processing is applied to theoverlapping area as Case 3(at step 270).

In other words, when both the image A and the image B are a planarimage, the image processing is applied to the overlapping area as Case1; when either the image A or the image B is an embossed image, which isan image three-dimensionally expressed with a foaming toner and colortoners placed on the foaming toner, the image processing is applied tothe overlapping area as case 2; and when both the image A and the imageB are an embossed image, the image processing is applied to theoverlapping area as Case 3.

When the image processing has been applied as either of the Cases 1 to3, it is determined whether there is an overlap between images that hasnot been subjected to the image processing (at step 280). Then, when itis determined that there is an overlap between images that has not beensubjected to the image processing (YES at step 280), the images whichare overlapped one over another are identified (at step 210). When it isdetermined that there is no overlap between images that has not beensubjected to the image processing (NO at step 280), image formation datais created from the image data (at step 290).

Next, the flow of image processing of each of the Cases 1 to 3 will bedescribed in detail with the use of the respective flow charts.

FIG. 5 is a flow chart illustrating the flow of image processing of Case1 where both the image A and the image B are a planar image.

First, the priority ranks in representing the image A and the image Bare determined (at step 251).

When it is determined that the image A is to be represented, givenpriority over the image B (that the priority rank for the image A ishigher than that for the image B) (YES at step 251), the overlappingarea where the image A and the image B are overlapped one over anotheris extracted (at step 252), and the image in the overlapping area of theimage B, which priority rank is lower, is deleted (at step 253) forcreation of image formation data.

On the other hand, when it is determined that the image B is to berepresented, given priority over the image A (that the priority rank forthe image B is higher than that for the image A) (NO at step 251), theoverlapping area where the image A and the image B are overlapped oneover another is extracted (at step 254), and the image in theoverlapping area of the image A, which priority rank is lower, isdeleted (at step 255) for creation of image formation data.

In the present embodiment, the image in the overlapping area that has alower priority rank is deleted before image formation data beingcreated. Alternatively, as in a case where the image in the overlappingarea is represented while utilizing the image that has a lower priorityrank, image formation data may be created without deleting the imagewhich has a lower priority rank, as required.

Such a processing can be instructed, for example, by adding informationfor instructing the method of image processing to the image data in theimage editing device, and transmitting the image data to which theinstruction information has been added, to the image forming device.

FIG. 6 is a conceptual drawing illustrating an example of imageprocessing of Case 1. For example, as shown in FIG. 6( a), when aparticular image having an area 52 where parts of an image A50 and animage B51, which are planar images, are overlapped one over another isto be formed into an image on the recording paper, the image processingfor deleting the image in the overlapping area 52 of the image A50,which has a lower priority rank, is carried out, as shown in FIG. 6( b),before image formation data being created, and as shown in FIG. 6( c),the image is formed into an image on a recording paper 53 such that apart of the image B51, which has a higher priority rank, is overlappedon the image A50, which has a lower priority rank.

When image formation data is to be created with the image which has alower priority rank being not deleted, as in a case where the image inthe overlapping area is to be expressed by utilizing the image which hasa lower priority rank, the image A is first formed into an image withthe image in the overlapping area as shown in FIG. 6( b) being notdeleted, and then the image B is formed into an image.

Next, FIG. 7 is a flow chart illustrating the flow of image processingof Case 2 where one of the image A and the image B is a planar image,and the other is an embossed image.

First, the priority rank for the embossed image is determined from thepriority ranks in representing the image A and the image B (at step261).

When it is determined that the image which is an embossed image is notto be represented, without being given priority over the image which isa planar image (that the priority rank for the image which is anembossed image is lower) (NO at step 261), the overlapping area wherethe image A and the image B are overlapped one over another is extracted(at step 262), and the color image in the overlapping area of the imagewhich is an embossed image is deleted (at step 263) for creation ofimage formation data.

On the other hand, when it is determined that the image which is anembossed image is to be represented, given priority over the image whichis a planar image (that the priority rank for the image which is anembossed image is higher) (YES at step 261), image formation data iscreated with the image in the overlapping area of the image which is aplanar image being not deleted.

FIG. 8 is a conceptual drawing illustrating an example of imageprocessing of Case 2. As shown in FIG. 8( a), for example, when aparticular image having an area 62 where parts of an image A60, which isan embossed image, and an image B61, which is a planar image, areoverlapped one over another, is to be formed into an image on therecording paper, the image processing for deleting the image in theoverlapping area 62 of the image A60, which has a lower priority rank,is applied, as shown in FIG. 8( b), before image formation data beingcreated, and as shown in FIG. 8( c), the image is formed into an imageon a recording paper 63 such that a part of the image B61, which has ahigher priority rank, is overlapped on the image A60, which has a lowerpriority rank.

In the present embodiment, when the priority rank for the image which isa planar image is higher than that for the image which is an embossedimage, only the color image in the overlapping area of the embossedimage is deleted.

When, for example, a particular planar image has a higher priority rank,it is preferable that the image processing is applied such that theplanar image in the overlapping area is prevented from beinginadequately represented resulting from a part of the planar image beingformed into an image on the foaming toner; such that, the color for theborder area between the planar image and the embossed image is deepenedso that the color for that area is prevented from being thinned by theexpansion of the foaming toner, for example.

Incidentally, when a particular image with which the embossed image hasa priority rank higher than that of the planar image is to be formedinto an image (for example, when a particular image with which anoverlapping area 72 where an image A70, which is an embossed image, andan image B71, a planar image, are overlapped one over another isprovided, as shown in FIG. 9( a), and the priority rank for the imageA70 is higher than that for the image B71 is to be formed into animage), image formation data for forming a planar image is created withthe image processing for deleting the image in the overlapping area ofthe planar image being not carried out, which is followed by forming theplanar image into an image, and then forming an embossed image forformation of an image on a recording paper 73 as shown in FIG. (b).

This is because an embossed image consists of the foaming toner forexpressing an embossed image and a color image which is formed byplacing color toners on the foaming toner, and thus the planar image inthe overlapping area is covered with the foaming toner, which means thatthe planar image can have no effect on the color image. Therefore, withthe planar image in the overlapping area being deleted, the embossedimage in the overlapping area can be satisfactorily formed into animage.

In the present embodiment, only the color image in an embossed image isdeleted. Alternatively, the system may be configured such that the imageprocessing is carried out to cause the color image to be deletedtogether with the image provided by the foaming toner for expression ofan embossed image for the image formation.

Also, when the priority rank for the embossed image is higher than thatfor the planar image, the planar image in the overlapping area is notdeleted. Alternatively, the system may be configured such that theplanar image in the overlapping area is deleted for directly depositingthe foaming toner on the recording paper or minimizing the consumptionof the color toner(s).

FIG. 10 is a flow chart illustrating the flow of image processing ofCase 3 where both the image A and the image B are an embossed image.

First, the priority ranks in representing the image A and the image Bare determined (at step 271).

When it is determined that the image A is to be represented, givenpriority over the image B (that the priority rank for the image A ishigher than that for the image B) (YES at step 271), the overlappingarea where the image A and the image B are overlapped one over anotheris extracted (at step 272), and the image in the overlapping area of theimage B, which priority rank is lower, is deleted (at step 273) forcreation of image formation data.

On the other hand, when it is determined that the image B is to berepresented, given priority over the image A (that the priority rank forthe image B is higher than that for the image A) (NO at step 271), theoverlapping area where the image A and the image B are overlapped oneover another is extracted (at step 274), and the image in theoverlapping area of the image A, which priority rank is lower, isdeleted (at step 275) for creation of image formation data.

In the present embodiment, the image in the overlapping area that has alower priority rank (the foaming toner and the color image) is deleted.However, in such a case where the image which has a lower priority rankis to be made the most of to express the image in the overlapping area,image formation data may be created with only the foaming toner or thecolor image being deleted, as required.

FIG. 11 is a conceptual drawing illustrating an example of imageprocessing of Case 3. As shown in FIG. 11( a), when a particular imagehaving an overlapping area 82 where parts of an image B81 and an imageA80, which are both an embossed image, the priority rank for the imageB81 being higher than that for the image A80, are overlapped one overanother, is to be formed into an image, the image processing fordeleting the image in the overlapping area 82 of the image A80, whichhas a lower priority rank, is applied, as shown in FIG. 11( b), beforeimage formation data being created, and as shown in FIG. 11( c), theimage is formed into an image on a recording paper 83, because theembossed images are overlapped one over another.

In this example, both the image A and the image B are embossed images,and the heights of the images when formed into an image are equal toeach other, thus no embossed boundary is basically provided in theborder area between the image A and the image B after image formation.

When it is determined that both the image A and the image B are embossedimages, it may be so configured that an image formation data is createdwith the image processing being not applied to the overlapping area, andby forming the image A into an image before forming the image B into animage, an image is formed in which parts of the image A and the image Bare overlapped one over another.

For example, as shown in FIG. 12( a), when an image having a partiallyoverlapping area 92 where parts of an image A90 and an image B91, whichare both an embossed image, are overlapped one over another is to beformed into an image on the recording paper, an image formation data iscreated with the image processing for deleting the image in theoverlapping area of the image which priority rank is lower being notcarried out. Then as shown in FIG. 12( b), the image is formed into animage on a recording paper 93 such that a part of the embossed image 91which priority rank is higher is overlapped on the embossed image A90which priority rank is lower.

1. An image forming device which forms an image into an image on arecording paper, comprising: means for determining that there is an areawhere two images are overlapped one over another at least partially; andmeans for determining attributes of these two images, wherein for animage having a specific attribute of these two images, no image isdeleted even in the overlapping area.
 2. An image forming device whichforms an image into an image on a recording paper, comprising: means fordetermining that there is an area where two images are overlapped oneover another at least partially; means for determining priority rankswhich represent a top or bottom in overlapped status of these two imagesin the overlapping area; and means for forming an image which priorityrank is lower, and thereupon, forming an image which priority rank ishigher, in the overlapping area.
 3. The image forming device of claim 2,further comprising means for determining attributes of these two imagesin the overlapping area, wherein these two images are an image having aspecific attribute, and an image having another attribute, when theimage having the specific attribute has a priority rank lower than thatfor the image having the another attribute, the image having thespecific attribute is formed into an image, and thereupon, the imagehaving the another attribute is formed into an image in the overlappingarea, and when the image having the specific attribute has a priorityrank higher than that for the image having the another attribute, theimage having the specific attribute is formed into an image, and theimage having another attribute being not formed into an image in theoverlapping area.
 4. The image forming device of claim 3, furthercomprising means for selecting either forming the image having thespecific attribute in the overlapping area into an image, and thereupon,forming the image having the another attribute into an image, or formingthe image having the specific attribute in the overlapping area into animage, and not forming the image having the another attribute into animage, when the image having the specific attribute has a priority ranklower than that for the image having the another attribute.
 5. The imageforming device of claim 4, wherein, when both of these two images arethe image having the specific attribute or the image having the anotherattribute, the image which has a higher priority rank is formed into animage, and the image which has a lower priority rank is not formed intoan image in the overlapping area.
 6. The image forming device of claim4, wherein an attribute of the image having the specific attribute is anembossed image.
 7. The image forming device of claim 3, wherein, whenboth of these two images are the image having the specific attribute orthe image having the another attribute, the image which has a higherpriority rank is formed into an image, and the image which has a lowerpriority rank is not formed into an image in the overlapping area. 8.The image forming device of claim 7, wherein an attribute of the imagehaving the specific attribute is an embossed image.
 9. The image formingdevice of claim 3, wherein an attribute of the image having the specificattribute is an embossed image.
 10. The image forming device of claim 3,wherein, when both of these two images are the image having the specificattribute or the image having the another attribute, the image which hasa higher priority rank is formed into an image, and the image which hasa lower priority rank is not formed into an image in the overlappingarea.
 11. The image forming device of claim 3, wherein an attribute ofthe image having the specific attribute is an embossed image.
 12. Animage forming method for forming an image into an image on a recordingpaper, comprising the steps of: determining an overlapping area wheretwo images are overlapped at least partially, determining priority rankswhich represent a top or bottom in an overlapped status of these twoimages in the overlapping area, and forming an image which has a lowerpriority rank into an image, and thereupon, forming the image which hasa higher priority rank into an image.
 13. The image forming method ofclaim 12, further comprising the step of determining attributes of thesetwo images in the overlapping area, wherein, when it is determined thatboth of these two images are an image having a specific attribute and animage having another attribute, the image having the specific attributeis formed into an image, and thereupon, the image having the anotherattribute is formed into an image in the overlapping area when the imagehaving the specific attribute has a priority rank lower than that forthe image having the another attribute, and the image having thespecific attribute is formed into an image, and the image having theanother attribute is not formed into an image in the overlapping areawhen the image having the specific attribute has a priority rank higherthan that for the image having the another attribute.
 14. The imageforming method of claim 13, wherein an attribute of the image having thespecific attribute is an embossed image.